A particle moves under a force F = −k x. The motion is:

1. F = −k x is the linear restoring force characteristic of a spring (Hooke's law). 2. By Newton's second law, m ẍ = −k x ⇒ ẍ = −(k/m) x. 3. This is the SHM equation with angular frequency ω = √(k/m). 4. The total energy ½ k x² + ½ m ẋ² is conserved — spring PE + KE. _Source: NCERT Class 11 Physics Ch 5, §5.8 (spring PE) + Ch 13 SHM connection_